The present invention relates to a mixer for a double cartridge dispenser having at least two storage cylinders whose volumetric ratio is different from 1:1, comprising a mixer housing which is attachable to the cartridges and a mixing helix group which is arranged therein, the two dispensing openings of the cartridges communicating with the inlet portion of the mixing helix group. Such mixers are known, e.g., from EP-B-121,342, and they have the function of intimately mixing both components dispensed from the dispensing cartridges in order to prepare the components for their application.
In the case where both supply cylinders are approximately of the same volume and also comprise approximately equal dispensing openings, the mixing of the two components does not pose any problems from the outset. However, when the supply cylinders have essentially different volumes--which requires different cross-sectional areas because the supply cylinders have the same length on account of their manufacture and operation--and comprise outlet openings of, e.g., a ratio of 10:1, there is a risk that when the dispensing operation is started, the component from the larger supply cylinder fills the mixing helix group of the mixer due to different influences such as different elasticities of the two cartridge cylinders, so that the second component having a smaller volume is suppressed. Due to the fact that the second component is generally the hardener and that a mixture of components with an insufficient amount of hardener is useless, it is common practice, in order to stabilize the partial flows of the desired proportioning, to dispense a certain quantity which is discarded before being able to start the actual application of the mixture. Besides the loss of component substance, these dispensed substances cannot harden and may lead to disposal problems.